1. Field of the Invention
The present invention relates to improved hydrocarbon conversion and polymerization catalysts.
2. Prior Art
Aluminum halides, e.g., aluminum chloride, usually positioned on a variety of solid adsorbent surfaces, have been extensively employed as catalysts for many hydrocarbon conversion reactions. Such catalysts have found wide-spread use in alkylation, isomerization, and cracking reactions. Although aluminum halides may be employed alone, i.e. as bulk catalysts, or as a liquid complex with a variety of organic compounds, they are most conveniently employed in a form wherein they are adsorbed on an adsorbent material support such as alumina, silica, charcoal, bauxite, etc.
A common method for preparing such supported catalysts comprises forming an aluminum halide vapor in the presence of a suitable adsorbent material whereby the aluminum halide is adsorbed by the support surface. The aluminum halide may simply be vaporized in the so-called sublimation procedure. According to another procedure, aluminum chloride vapors are admixed with a carrier gas, i.e., a hydrocarbon, and contacted with the adsorbent material.
Optionally, molten aluminum chloride can be contacted with the adsorbent material and excess aluminum halide removed by vaporization.
According to another procedure, a solution of aluminum halide and a hydrocarbon can be passed in contact with the absorbent material until the desired amount of aluminum halide has been adsorbed by the support material.
An improved method is described in U.S. Pat. No. 3,248,343 wherein aluminum halide vapor is actually reacted with the surface hydroxyl groups on an adsorbent material to form --O--AlCl.sub.2 groups. The resulting reaction product is then "associated" with hydrogen halide to form a particularly active hydrocarbon conversion catalyst.
U.S. Pat. No. 4,066,716 suggests that an active alkylation catalyst can be formed by contacting a chlorided alumina composite catalyst with vaporized aluminum halide to add additional chlorine to the catalyst.
U.S. Pat. No. 2,927,087 describes a process wherein an aluminum halide is vaporized onto a refractory oxide and subsequently heated at a temperature above 300.degree. C. to remove any unreacted aluminum halide. It is suggested in the patent that there is an actual chemical reaction between the vaporized aluminum halide and the refractory oxide surface.
It is an object of the present invention to provide new and improved hydrocarbon conversion catalysts formed by a unique and novel method and their use in hydrocarbon conversion procedures.